Waiting for monitor enty messages in thread dump

Question

Hi,
I've a thread dump of a container in a Oracle Application Server 9.0.4.1 (running 1.4.2_07) right before restart because off low memory and a lot of threads in this dump are in this state:
"AJPRequestHandler-ApplicationServerThread-1588" prio=1 tid=0x37634bf8 nid=0x1982 waiting for monitor entry [43f22000..43f2386c]
can anyone tell me what this means? Google didn't reveal anything useful.
Another thing I don't understand although it seems it doesn't do any harm:
"AJPRequestHandler-ApplicationServerThread-1630" prio=1 tid=0x09011a68 nid=0x1982 in Object.wait() [40276000..4027686c]
at java.lang.Object.wait(Native Method)
- waiting on <0x6624e628> (a java.util.HashMap)
at java.lang.Object.wait(Object.java:429)
at java.net.InetAddress.checkLookupTable(InetAddress.java:1109)
- locked <0x6624e628> (a java.util.HashMap)
at java.net.InetAddress.getAddressFromNameService(InetAddress.java:1048)
at java.net.InetAddress.getLocalHost(InetAddress.java:1188)
at com.evermind.server.http.EvermindHttpSession.encodeSession(EvermindHttpSession.java:414)
at com.evermind.server.http.HttpApplication.createSession(HttpApplication.java:1599)
why is this thread waiting for a lock itself has?
Thanx for any help and hints in advance.
Regards,
Ingo

Answer 1

Hi,
I've a follow-up question, I have the following thread in several thread dumps:
"AJPRequestHandler-ApplicationServerThread-717" prio=1 tid=0x4046b988 nid=0x3dd3 waiting for monitor entry [3845e000..3845e86c]
     at java.net.Inet4Address.getAddress(Inet4Address.java:287)
     at com.evermind.server.http.StandardRequestLogger.appendIP(StandardRequestLogger.java:187)
     at com.evermind.server.http.StandardRequestLogger.log(StandardRequestLogger.java:45)
     - locked <0x663b2088> (a com.evermind.server.http.StandardRequestLogger)
     at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:906)
     at com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:208)
     at com.evermind.server.http.AJPRequestHandler.run(AJPRequestHandler.java:125)
     at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
     at java.lang.Thread.run(Thread.java:534)
What is the monitor this thread is waiting for? According to the source in Inet4Address at line 287 the method tries to create a new byte array... is there some system monitor which can't be seen in the thread dump?
This thread holds a lock (0x663b2088) 46 other threads are waiting for...
Thanx in advance for any hints.
Regards,
Ingo